Jacobaea vulgaris, ragwort

Summary

Ragwort is one of today's most notorious plants but, in reality, the dead
plant, unseen in a bale of hay, is far more harmful than all the
living plants seen along roadsides and in fields. There are very few
proven deaths even from conserved forage.

'Poisonous Plants 1-2-1' video

This short video summarising the story of common ragwort is just one of
a series.

Family

Asteraceae

Meaning of the Name

In Scotland it is called stinking Willie
because it spread in the path of William, Duke of Cumberland’s
Culloden campaign.

The Scottish connection between Jacobaea vulgaris and the Duke of
Cumberland leads some people to ask if the name comes from that.

John
Gerard uses the name Senecio jacobaea (the name it had before
Jacobaea vulgaris) so it predates the 1746 Battle
of Culloden where it acquired the name ‘Stinking Willie’ after the
Duke of Cumberland. The name, therefore, has nothing to do with the Jacobites.

Jacobaea
Possibly derived from St James or Jacobus. The phrase ‘conditio
Jacobaea’ is used to mean ‘If the Lord wills it’ and is said to come
from St. James’ instruction to examine all plans to see if they meet
God’s will. It may be that the pernicious ragwort could only
be tolerated on the basis that it was part of God’s will. Images of
St James tend to show him as an older man with grey or greying hair,
somewhat unkempt. It may be that the ragwort was thought to
look like St James’ beard.

vulgarisCommonplace, usually given to the most common species in a genus.

The plant is sometimes still referred to by the name Senecio
jacobaea.

Common Names and Synonyms

ragwort, common ragwort, stinking Willie, Benyon's delight*

*I love that plant names continue to evolve and that new names
get coined. 'Benyon's delight' as a name for common ragwort was, I
believe, first used by Dusty Gedge in
this video (at 3m 45s) about butterflies. It follows the 2011
Facebook comments by Richard Benyon, the then government minister
responsible for biodiversity. You can read the full story
in
this blog entry.

How Poisonous, How Harmful?

Contains pyrrolizidine alkaloids (PAs) which are hepatotoxic and can
cause complete liver failure.

There is no evidence that ragwort causes harm by contact or
inhalation. In fact, there is very little evidence of harm to
humans resulting from ragwort except for those with pre-existing
liver damage and a couple of cases where
very young children were given large amounts of an herbal tea made
with ragwort which was said to be a cough medicine.

It has been found that, although the taste is
unpleasant, cattle will eat ragwort if there is nothing else
available. Interestingly, when returned to normal grazing land
these animals are found to continue eating ragwort. This leads to
speculation that ragwort is addictive and it should be noted that
there are species of Senecio which have been used by Mexican Indians
for their psychoactive properties.

Though there is no evidence of its harming healthy humans it may
be
more of a
problem for horses. This is because living ragwort is extremely unpleasant to
the taste and animals will ignore it if there is something else
available. If it gets into hay, however, it has lost the taste but,
being one of the few plants which retains its toxicity after death*,
it will poison horses fed on the hay if a large enough quantity is
consumed.

*This is an over-simplification. UK government
researchers found that the PAs in common ragwort degrade over time
and the speed of that decay seems to depend on the conditions in
which the cut ragwort is stored. Although the paper
(abstract here) was aimed at evaluating a new testing method, it
does conclude that there may be better ways of disposing of ragwort
than the incineration usually undertaken.

The symptoms it causes are described by the names given to its
effects, ‘Walking Disease’ and ‘Sleepy Staggers’. It can cause
blindness prior to death. Death comes from liver failure which
results in the release of ammonia into the bloodstream which, in
turn, destroys the brain.

It is often said that PAs are a cumulative poison. That is
not the case but the liver damage caused is slow to repair so
that the effects can be cumulative if consumption takes place
over a relatively short time.

Misinformation about ragwort is very persistent and the number of
horse deaths from ragwort poisoning is especially prone to gross
exaggeration but there are a
couple of websites where the creators have gone to a lot of trouble
to look at evidence and debunk the lies and myths.

The first is
'Ragwort Myths and Facts' and the second is
'Ragwort Facts'. The second is a purely text site with lots of
information. What makes the first site so interesting is that it was
created by a Dutch horse owner who took the time to look into the
information about ragwort and found so much of it to be wrong. My
link is to her English language site but
the Dutch original has a great many useful photographs to aid
identification.

Watch a Video about Jacobaea vulgaris, ragwort

Jacobaea vulgaris, common ragwort

Incidents

There are no cases that have ever been reported where poisoning
to human beings has been found to have been caused by ragwort.

The only recorded cases of poisoning due to plants of the genus
Jacobaea or Senecio are all where a plant had been used to produce an herbal tea
and long-term consumption had allowed the build up of liver damage.

Based on known levels required to poison horses, it has been
estimated that a human would need to consume 14lb, 6Kg, of ragwort
to ingest a lethal dose in one sitting.

There has been no research done on the effects of handling
ragwort, which in itself suggests that this is not a problem, but
research on Symphytum spp., comfrey, has shown that absorption of
pyrrolidizine alkaloids through the skin of rats resulted in blood
levels twenty to fifty times lower than those resulting from
ingestion of the same amount. This suggests that a person would need
to have, at least, 120Kg of ragwort applied to their skin to achieve
the same effect as ingesting the 6Kg referred to above.

There are, however, other compounds in ragwort that can produce
contact dermatitis. For this reason, the wearing of gloves is also
advised when removing the plant. Unfortunately, the advice to wear
gloves gets cited as proof that humans can absorb enough PAs through
the skin to be poisoned.

There is one claim that absorption by the skin has been
demonstrated but, it seems, only a single test was performed, without
proper controls, and there has been no replication. The observed
changes to the subject's liver cannot therefore be taken as proof of
skin absorption. This claim was made by Professor Derek Knottenbelt.
See the blog entries for
11th
October 2011 and
6th
September 2011 for more on the unreliability of the professor's
statements.

Folklore and Facts

It is an injurious weed under the Weeds Act of 1959 and
landowners could be ordered to deal with it. Contrary to what is
often said, it is not illegal to have it growing and landowners are
not obliged to remove it. It is also not 'notifiable'. Under the
Weeds Act, if the ministry becomes aware of a potentially harmful
area it can order removal.

Ragwort is one of five plants included in the Weeds Act of 1959.
The full list is;
common ragwort
spear thistle
creeping or field thistle
curled dock
broad-leaved dock.

The provisions of the Weeds Act still apply to ragwort. The Ragwort Control Act
passed on 20 November 2003, which was
sponsored by The British Horse Society, originated as a Private
Member’s Bill, and was presented to Parliament by John Greenway MP.
The Government gave its backing to the Bill and ensured its
successful passage through Parliament. The Act came into force on 20
February 2004.

Ragwort is important to
biodiversity

The Act called for the creation of a Code of Practice (COP) in
respect of ragwort and the code was issued in July 2004. The purpose
of the COP is to give a measure for determining whether action under
the Weeds Act is appropriate.

The COP deals with the identification of ragwort, its safe handling,
control and disposal and sets out the duties of livestock owners,
forage producers and land owners.

One very important point to make is that it is NOT a requirement to
remove ragwort in every case though it is the responsibility of the
occupier of the land to take the appropriate action.

There is a great deal of misinformation about
ragwort. A visitor to the Alnwick Garden Poison Garden was
heard to say that she thought it was illegal to allow ragwort to
grow. Her son, a smallholder, had been instructed to remove
all ragwort from his land including that in a Site of Special
Scientific Interest (SSSI). The COP says that English Nature
MUST be consulted before ragwort is removed from an SSSI or other
protected area of land.

The COP talks about the importance of ragwort to biodiversity and
goes on to set out three risk levels:

High Risk:
• ragwort is present within 50m of land used for grazing by horses
and other animals or land used for feed production.
Medium Risk:
• ragwort is present within 50m to 100m of land used for grazing by
horses and other animals or land used for feed production.
Low Risk:
• ragwort or the land on which it is present is more than 100m from
land used for grazing by horses and other animals or land used for
feed production.

(Crown copyright material is reproduced with the permission
of the Controller of HMSO and the Queen’s Printer for Scotland)

Immediate action to remove ragwort is only required for high risk
areas. For medium and low risk areas, it is a matter of ‘wait
and see' but with plans being put in place in case the area becomes
high risk.

The COP gives lots of information on removal, disposal and handling
techniques. It calls for the wearing of strong gloves, keeping
arms and legs covered and the use of facemasks to prevent
inhalation. This reinforces the internet myths about ragwort being
absorbed through the skin or inhaled. It is true that some
people develop contact dermatitis from handling ragwort and
mechanical damage can be caused by abrasion if a large number of
plants are pulled up but the PAs are not absorbed through the
skin. As far as inhalation goes, the 2003 draft
of the COP says that wearing a facemask is ‘to reduce the risk of hay fever’ but
this wording is not present in the final version.

In April 2016, the COP was
officially withdrawn but, bizarrely, in May 2016 a
government minister told parliament that the code had
not been withdrawn. No reason for the withdrawal seems to
have been given and the
new advice that replaces it is incomplete and confusing.

Ragwort was introduced in New Zealand in the 1800s. It
thrived and became a noxious weed, which farmers sought to
eliminate. In the 1930s, sodium chlorate was used as a
weed-killer to try and bring ragwort under control. Sodium
chlorate is very volatile and fumes penetrated cotton clothing
making the clothing flammable.

Amongst the incidents reported was the farmer out riding when
the friction between his saddle and his clothing caused the
sodium chlorate to ignite. In another case, a farmer went
straight from work to see his newborn son. When he struck a
match to see the child better, his clothes caught fire and he
burned to death.

In spite of what has been described as an epidemic of
exploding trousers, farmers were so pleased to find something
that would control the spread of ragwort that they continued to
use it until 1946 when a new type of weed-killer became
available.

In 2006, the US TV programme 'Mythbusters' demonstrated the
truth of the New Zealand experience which many people had
assumed to be apocryphal.

Earlier Blog Entries

You can read more about ragwort and the flaws in the arguments of
those who claim it must be eradicated in these blog entries (most
recent first);